# Star ccm+ DFBI problem

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 October 1, 2019, 10:51 Star ccm+ DFBI problem #1 New Member   siam Join Date: Jul 2019 Posts: 4 Rep Power: 2 Hello everyone, I'm confused about DFBI Rotation and Translation. Is that a two-way fsi or one-way? By the help manuel, it says mechanical body is rigid structure so there will be no deform of the mechanical body and no deform displacement that gives force to the continuum body. It does not tell if the motion(translation or rotation) of the mechanical body will tranfer force and moment back to the continuum body(If it is true, is that consider as a two-way fsi?). Thank you!

 October 3, 2019, 23:50 #2 New Member   siam Join Date: Jul 2019 Posts: 4 Rep Power: 2 I've read some paper about DFBI, it is not coupled with and structure solver which there will be no data transform between fluid solver and structure solver. It is not any types of fluid structure interaction.

 October 4, 2019, 23:26 #3 Senior Member   Ping Join Date: Mar 2009 Posts: 376 Rep Power: 14 in the strict sense of the term fsi does involve a structural solver to model the deformation of the structure and if you do a search for fsi in the star help the first two topics found give you a good explaination. and it also explains how to use the inbuilt structural solver in star to do 'full' fsi in star including using dfbi to capture the 6dof motion. dfbi on its own is two way coupled between the body and the fluid in that the fluid motion affects the body motion and the body motion affects the fluid flow but the body remains rigid - unless you also include the structural solver or link to an external code.

October 7, 2019, 14:35
#4
New Member

siam
Join Date: Jul 2019
Posts: 4
Rep Power: 2
Quote:
 Originally Posted by ping in the strict sense of the term fsi does involve a structural solver to model the deformation of the structure and if you do a search for fsi in the star help the first two topics found give you a good explaination. and it also explains how to use the inbuilt structural solver in star to do 'full' fsi in star including using dfbi to capture the 6dof motion. dfbi on its own is two way coupled between the body and the fluid in that the fluid motion affects the body motion and the body motion affects the fluid flow but the body remains rigid - unless you also include the structural solver or link to an external code.
Thank you Ping! I've read the star help. I do found how the fluid affects the body motion but i dont see how the body motion affects the fluid field in the manual.

 October 8, 2019, 03:44 #5 Senior Member   Ping Join Date: Mar 2009 Posts: 376 Rep Power: 14 well do the boat in waves tutorial or the life boat one and it will be pretty obvious

October 8, 2019, 14:09
#6
New Member

siam
Join Date: Jul 2019
Posts: 4
Rep Power: 2
Quote:
 Originally Posted by ping well do the boat in waves tutorial or the life boat one and it will be pretty obvious
I've done tutorial about that. I can clearly see that the strucure motion is affecting the fluid part. I'm just trying to figure out the algorithm and details about the strucure to fluid part of this method.

 Tags dfbi, fsi, fsi 2-way, fsi 2-way coupling, star ccm+